INHERITED PREDISPOSITION TO COLON-CANCER

Colorectal cancer is one of the most common malignancies in the United States. Although both genetic and environmental factors play a role i n colorectal tumorigenesis, recent advances in genetics have more clea rly defined the impact of inheritance in the multistep process of the disease. Researchers have identified single genes that confer a suscep tibility to familial adenomatous polyposis (FAP) and hereditary nonpol yposis colorectal cancer (HNPCC). Because these genes are inherited in an autosomal dominant fashion, offspring of carriers have a 50% chanc e of inheriting the gene mutation and its associated risk The FAP gene , when mutated, initiates the neoplastic process. HNPCC gene mutations disrupt mismatch repair, thus inducing progression of tumor formation . Discovery of these genes has helped our understanding of sporadic co lon cancer as well. Genetic testing for the FAP and HNPCC genes is now available, and results of this testing have implications for surveill ance and management. In addition, resting raises complex psychosocial and ethical issues. At present, genetic testing is primarily conducted in the research setting, but it will soon be available in the clinica l arena. To prepare for the challenges that these new advances will pr esent, nurses must begin now to enhance their knowledge of genetics an d its application to oncology.